Customs are to step up inspections at Chek Lap Kok airport and work with overseas law enforcement authorities to stop drug traffickers smuggling cannabis from South Africa to the city, a senior customs officer said.

This follows the arrest of two women who arrived from Johannesburg with a total of 45kg of cannabis hidden in their luggage on Tuesday and Wednesday.

Ben Leung Lun-cheung, head of the Customs Drug Investigation Bureau, said initial investigations indicated that the two cases were linked and the two South African women were hired as couriers by the same drug trafficking syndicate.

He said the value of the seizure was about $3 million and it was the largest seizure of cannabis this year.

'We believe the drugs were for distribution in Hong Kong and the mainland. There may be further arrests in or outside Hong Kong,' he said. Mr Leung said drug traffickers previously smuggled cannabis direct from Cambodia but since last year the trend was from South Africa.

Customs officers arrested several couriers from South Africa at the airport last year but each carried less than 2kg of cannabis. 'It appears that drug dealers have given up the shorter route from Cambodia and resorted to a new and longer route from South Africa to smuggle cannabis into Hong Kong,' he said.

Hong Kong authorities were very concerned about this rising trend of cannabis smuggling.

'We will enhance intelligence collection and step up inspection at the airport. We will also seek international co-operation to combat the problem,' Mr Leung said.

He said the two women would be charged with trafficking in dangerous drugs and they would appear in Tsuen Wan Court today.